Device to reduce oil losses



April 1965 w. ROLLINGER ETAL 3,176,912

DEVICE TO REDUCE OIL LOSSES Filed June 11, 1962 Fig. 2

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Jn venlors: ma ROLLl/VGER ATTORNEY United States Patent 3,176,912 DEVI'CE TG REDUCE OIL LOSSES Willy Rollinger, Porz-Westhoven, and Helmut Bode, Bergisch-Gladbach, Germany, assignors, by mesne assignments, to Leybold Holding A.G., Zug, Switzerland Filed lune ll, 1962, Ser. No. 201,702 8 Claims. (Cl. 230-205) The invention concerns a device to reduce oil losses occurring in operating rotation vacuum purnps with exhaust valves which are immersed in oil.

When in operation, these pumps draw out large quantities of air through the exhaust valve which is immersed in oil against comparatively high intake pressures. Oil which is being thereby pulled along in the form of mist droplets is lost to pump operation. The resulting oil consumption in known pumps may amount to cm. h. at Nm. of conveyed air.

Attempts have been made to decrease this oil consumption and to collect the oil in a space which will make it possible to return the oil to the inside space of the pump. It is a well known fact that for such a purpose the gases leaving the valve through the oil are made to flow against a deflecting plate placed above the oil level in order to turn them around repeatedly in their progress. Attempts have been made to an added whirling motion to the ejected gases by means of an arrangement consisting of built-in propeller-like blades. A further known method of oil separation consists in designing the repeated deflection in such a way that the mixture of oil vapor and air which enters a tube after leaving the valve is directed towards the center of an S-shaped pipe system lying at right angles to the direction of discharge. In all of these known constructions only a certain coarse separation is achieved. Such separation, however, is not sufiicient, and, in addition, it does not prevent the formation of oil mist. Quite to the contrary, it might even partially promote such formation of oil mist as the result of whirling the larger drops.

The invention intends, therefore, not only to improve the coarse separation but also to separate the fine drops from the oil mist by guiding the mixture of oil vapor and air in a suitable manner. Accordingly, the characteristic feature of the invention is considered to be the fact that, in combination with the valve space lying within the range of the exhaust valve, tangential inlet ports of at least one cyclone separator element are provided for and that the ejection takes place towards the atmospheric side by means of a discharge tubing which is arranged concentrically inside the cyclone element.

The following design of the built-in cyclones is considered as being of advantage: the casing of the cyclone separator element consists of at least two differently tapered truncated cone sections and contains on the inside, within the range of half of its height, a guide body, in particular of a cone-shaped design, the apex of which is turned towards the inlet port of the cyclone discharge tubing. In addition, the formation of a spiral-like flow of the mixture of oil vapor and air is being supported by providing the area of the tangential inlet ports with otherwise known flow guide elements. The oil separation on the inside of the cyclone separator element is, furthermore, very favorably aifected by the fact that the cyclone discharge tubing is enclosed by a tubular par-t, with the discharge tubing extending beyond the latter, and that this tubular part is further equipped with a shield-like ring-shaped disc in the area of the bottom edges of the tangential inlet ports. The undesirable penetration of oil into the discharge tubing can be prevented in this manner.

For the purposes of assembly and maintenance it is of "ice great advantage that at least one detachable cyclone separator element is placed in a separation chamber located adjacent and preferably lateral to the valve space of the pump, whereby the separation chamber is provided with an exhaust chamber above the outlet orifice of the cyclone discharge tubing. This exhaust chamber is equipped with openings into which the cyclone discharge tubing, the latter partially extending beyond the end face of the cyclone separator element, can be inserted, preferably, thereby, interposing a sealing element. In this connec tion it is of advantage also to fasten the cyclone separator element by pressing the cyclone casing against bearing surfaces of the exhaust chamber by means of a detachable screw pressure device.

In addition, oil separation will be favorably affected if, especially in the case of pumps with several valves, several cyclone separator elements are installed parallel to each other and attached to the exhaust chamber. As a precaution against oil being still separated and collected in the exhaust chamber during prolonged operation at high intake pressures, a connecting pipe is pro vided for between the exhaust chamber and the oil sump of the oil supply chamber, whereby this connecting pip-e not only forms a Syphon-like seal in relation to the exhaust chamber by being partially filled with oil, but also serves to let the eventually collected oil flow 01f into the oil sump.

The drawing represents the diagrammatioal View of one form of construction of the invention, as follows:

FIG. 1 shows a cross-section of a rotary pump to which the invention has been applied,

FIG. 2 shows a lateral view of FIG. 1 with the side wall removed,

FIG. 3 shows a section along the center line of the cyclone separator element in accordance with the invention; and

FIG. 4 is a transverse section of the upper part of the cyclone of FIG. 3.

The pump casing 1 with a scooping chamber 2 contains a pump piston 3 which is made movable by means of an eccentric 4, whereby a flat slide valve 5 connected with the pump piston 3 is guided inside the connecting link 6 in such a manner as to enable the pump piston 3 to perform an oscillatory up-and-down movement, thereby conveying the gas, which has been sucked in through slits of the slide valve 5 into the scooping chamber 2, from the suction port 7 to the exhaust opening 9 by way of the suction chamber 8. On the way from the scooping chamber 2 to the exhaust opening 9 the gas must pass through the exhaust valve 10 which is superposed with oil, thereby pulling along oil in the form of droplets and vapor. The mixture of oil vapor and air spreads out in the separation chamber 11, which is adjacent and preferably lateral to the space occupied by valve Ill, whereby a large portion of the oil which had been pulled along in the form of droplets is being separated again. The conical cyclone separator elements 12 which are to be found in the separation chamber 11 take up the mixture now. This mixture is subjected to a spiral-like mo tion-in the form of construction given here, this motion is directed downwardsby means of which the oil is separated from the mixture to a substantial degree. The frusto-conical baflle 121 is positioned the cylindrical outlet tube 122 and directs exhaust gas upwardly into the exhaust chamber 13. The outlet tube 122 is equipped with an additional shielddike ring-shaped disc 123, so that the oil which might have condensed at the tubular piece 122 cannot reach the battle 121. A coneshaped guide. body 124 for the gases which are to be discharged rises to about one half of the height of the cyclone separator element 12.

The gas, coming from the outlet tube 122, flows through the exhaust chamber 13, to which all of the cyclones are attached, towards the exhaust opening 9. The cyclone separator elements 12 are clamped into the separation chamber 11 in such a manner that they not only extend at their upper end together with a portion of the outlet tube 122 into the exhaust chamber 13, wherebythe openings in the wall between the separation chamber 11 and the exhaust chamber 13 are sealed by means or packings 14, but that they can also be fastened at their lower end by means of the screw pressure device 125; A connecting tubing 15 leads from the exhaust chamber 13 to the oil' sump 16. I

The upper part of the cyclone, as clearly shown in FIG. 4, has inlet openings 126 which produce the cyclone eifect by admitting the moist air tangentially into the cyclones.

We claim: 1. The combination of a vacuum pump having an oil immersed exhaust valve with means for largely separating the oil from the air being exhausted, which comprises at least one cyclone separator composed of a vertical conical chamber with its large end upward, a cylindrical outlet tube set into the upper closed end of the conical chamber 7 and extending inwardly and coaxially one-third of the length of the chamber, an inner frusto-conical bafile within the outlet tube and fitted into the top of the tube, a dish baffie centrally supported in the cyclone'chamber and tangential openings near the top of the chamber to direct the wet gas from the pump exhaust in a helical path downwardly within the cyclone separator above the conical walls thereof. 7

' 2. A device according to claim 1, in which the lower port-ion of the outer cylindrical wall of said cylindrical can be inserted, preferably thereby interposing a sealing element. 7

4. The combination of a vacuum pump having an oil immersed exhaust valve with means for largely separating the oil from the air being exhausted, which comprises at least one cyclone separator having a vertical conical chamber with its large end upward, a cylindrical outlet tube extending coaxially inward at least one-fourth the length of the chamber and sealed into the closed top thereof, an annular projection near the lower end and on the outside of the outlet tube, a frusto-conical baflie,

within the tube and fitted to close the outer end of the tube and extending downwardly within it, the vertical chamber of said cyclone separator having inlet holes near the top extending tangentially through its wall to receive wet gas under pressure from the oil immersed exhaust valve of the pump and create a cyclone effect within, whereby the relatively dry gas escapes upwardly through the frusto-conical bafi le.

'5. A device according to claim 4, including an exhaust chamber positioned above said cyclone separator and in which the fastening of the cyclone separator element takes place by pressing the cyclone casing against the bearing surfaces of saidexhaust chamber by means of a detachable screw pressure device. 7

6. A device according to claim 4, in which several cyclone separator elements are installed parallel to each other andattached to said exhaust chamber.

7. The combination of a vacuum pump having an oil immersed exhaust valve with means for largely separating the oil from the air being exhausted, which comprises at least one cyclone separator having a substantially vertical conical casing with the large end closed at the top, with a cylindrical sleeve extending axially down from the closed top for approximately one-third of the length of the conical casing and extending outwardly through a hole in the closed top for a short distance to connect with the outlet air chamber, said cyclone separator having tangentially aranged inlet openings near the top to cause a downwardly swirling motion'of the exhaust gas from the exhaust valve of the pump.

8. The combination of a vacuum pump having an oil immersed exhaust valve with means for largely separating the oil from the exhaust which comprises at least one cyclone separator having a conical casing with its larger end closed, connected to receive the pump exhaust, an inner cylindrical open sleeve of intermediate size extending axially outward a short distance from a hole in the large end and inward therefrom for one-third of the length of the conical casing, an annular projection on the outside of the cylindrical sleeve near its inner end and and an inner firusto-conical sleeve within the intermediate cylindrical sleeve, the larger end of said frusto-conical sleeve being fitted to close the cylinder at its outer end and extending inwardly within and slightly below the inner end of the sleeve, said frusto-coni'cal sleeve being coaxial with the cylindrical sleeve;

References Cited in the file of this patent UNITED STATES PATENTS Fleuss Mar. 27, 1894 

1. THE COMBINATION OF A VACUUM PUMP HAVING AN OUL IMMERSED EXHAUST VALVE WITH MEANS FOR LARGELY SEPARATING THE OIL FROM THE AIR BEING EXHAUSTED, WHICH COMPRISES AT LEAST ONE CYCLONE SEPARATOR COMPOSED OF A VERTICAL CONICAL CHAMBER WITH ITS LARGE END UPWARD, A CYLINDRICAL OUTLET TUBE SET INTO THE UPPER CLOSED END OF THE CONICAL CHAMBER AND EXTENDING INWARDLY AND COAXIALLY ONE-THIRD OF THE LENGTH OF THE CHAMBER, AN INNER FRUSTO-CONICAL BAFFLE WITHIN THE OUTLET TUBE AND FITTED INTO THE TOP OF THE TUBE, A DISH BAFFLE CENTRALLY SUPPORTED IN THE CYCLONE CHAMBER AND TANGENTIAL OPENINGS NEAR THE TOP OF THE CHAMBER TO DIRECT THE WET GAS FROM THE PUMP EXHAUST IN A HELICAL PATH DOWNWARDOY WITHIN THE CYCLONE SEPARATOR ABOVE THE CONICAL WALLS THEREOF. 